A front jaw of this type, which has become known from EP-A-365 861, has a release plate which is pivotal about a transverse axis extending in the upper or lower housing area. The release spring surrounds the centrally oriented bolt, which acts as a pull rod for the release plate. The front end of the bolt is for this purpose screwed into an adjusting nut, against which is supported the front end of the release spring. This front end of the spring can thus be moved together with the adjusting nut relative to the housing, whereas the rear end of the release spring is supported on a housing-fixed wall.
A similar design is shown in AT-PS 396 337. A front jaw is described in this document in which two bent levers on a common bearing part are each hinged on a respective vertical axis, with this bearing part being supported upwardly and laterally pivotally on the housing. Both bent levers engage a release plate connected to a bolt and which is tensioned forwardly by the release spring through the adjusting screw. The release spring is supported housing-fixed directly in front of the release plate and is supported at its front end through a spring-receiving means guided on the housing on the adjusting screw. The adjusting screw and the bolt connected to the release plate are screwed together by means of a thread, thus creating the desired initial tension of the release spring. A pointer is furthermore mounted on the spring-receiving means to indicate the presetting of the release spring on an indicator which can be viewed through a window.
A disadvantage of the front jaws known from the two above-mentioned documents is that the indicator of the binding adjustment is changed during a stress on the release spring. This means that the indicator changes in an undesired manner already when the skier places the ski shoe into the binding. Furthermore, the housing is not closed off in front because of the support of the release spring and it can happen that the action of the release spring is affected, for example, by dirt, snow or ice.
DE-A 39 00217 discloses a very complicated design in which the bent levers are supported on lateral, two-arm levers. These lateral levers are loaded with pressure by a piston loaded by the release spring. Moreover, the piston is rearwardly extended for a backward release, with a crossbolt, sitting on the arms of the extension, being guided along a ski-fixed control curve. An axial rod extending through the release spring is supported housing-fixed at its rear end, whereas the front end of the rod is not supported on the front side of the housing. A pointer is in this front jaw connected to the spring-support plate.
It is a purpose of the invention to provide a front jaw in which the above-identified disadvantages are avoided, with the design being mechanically simple and well protected against environmental influences.